feat: playlist shuffle, lazy resolution, TTS ducking, kept repair

Music:
- #random URL fragment shuffles playlist tracks before enqueuing
- Lazy playlist resolution: first 10 tracks resolve immediately,
  remaining are fetched in a background task
- !kept repair re-downloads kept tracks with missing local files
- !kept shows [MISSING] marker for tracks without local files
- TTS ducking: music ducks when merlin speaks via voice peer,
  smooth restore after TTS finishes

Performance (from profiling):
- Connection pool: preload_content=True for SOCKS connection reuse
- Pool tuning: 30 pools / 8 connections (up from 20/4)
- _PooledResponse wrapper for stdlib-compatible read interface
- Iterative _extract_videos (replace 51K-deep recursion with stack)
- proxy=False for local SearXNG

Voice + multi-bot:
- Per-bot voice config lookup ([<username>.voice] in TOML)
- Mute detection: skip duck silence when all users muted
- Autoplay shuffle deck (no repeats until full cycle)
- Seek clamp to track duration (prevent seek-past-end stall)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/searx.py

@@ -6,6 +6,7 @@ import json
 import urllib.parse
 import urllib.request
 
+from derp.http import urlopen as _urlopen
 from derp.plugin import command
 
 # -- Constants ---------------------------------------------------------------
@@ -38,7 +39,7 @@ def _search(query: str) -> list[dict]:
     url = f"{_SEARX_URL}?{params}"
 
     req = urllib.request.Request(url, method="GET")
-    resp = urllib.request.urlopen(req, timeout=_FETCH_TIMEOUT)
+    resp = _urlopen(req, timeout=_FETCH_TIMEOUT, proxy=False)
     raw = resp.read()
     resp.close()